function Setting() {
    time = 0;
    score = 0;
}

Setting.prototype.change = function() {
    starttime = 3;
    let val_minutes = $('#minutes').val();
    let val_seconds = $('#seconds').val();
    if (val_minutes != '' || val_seconds != '') {
        valTime = 0;
        if (val_minutes != '') {
            valTime += parseInt($('#minutes').val()) * 60;
        }
        if (val_seconds != '') {
            valTime += parseInt($('#seconds').val());
        }
    }else {
        $('.error-msg').hide();
        $('.setting-nav').css('visibility', 'hidden');
        $('.start').show();
        valTime = 180;
        return;
    }
    if (valTime > 300 || valTime < 60) {
        $('.error-msg').css('display', 'block');
    }else {
        $('.error-msg').hide();
        $('.setting-nav').css('visibility', 'hidden');
        $('.start').show();
        return;
    }
}